Thanks for the reply.
I configured the AMD Control Center App to only run teracopy on the Intel card, so it is no longer an issue.

If this is not common, I don't mind closing as 'won't fix'.

I will also add that as far as I remember, it reproduced when connected to a 2nd screen, not on the main laptop screen.
This leads me to believe it might be a graphics card stack issue, which you don't necessarily can help.

If this is still something you want to research, I'll try to reproduce and recurd DbgView when I'm back from travel.
I can also use xperf to record more detailed information, and graphic stack events, if this is any interest.